Post working of mechanically alloyed products

ABSTRACT

Special post extrusion working of mechanically alloyed superalloys dispersion-strengthened with an oxide of a lanthanide series metal results in improved stress-rupture properties.

United States Patent 11 1 1111 3,909,309

Bomford Sept. 30, 1975 [54] POST WORKING ()F MECHANICALLY 3,494,807 2/1970 Stuart et al 148/1 1.5 F

ALLOYED PRODUCTS 3,660,049 5/1972 Benjamin 29/1825 3,746,581 7/1973 Caims et a1. 148/11.5 F [75] Inventor: Michael James mf rd, Bu ltk 3,749,612 7/1973 Benjamin et aL 148/11.5 F Switzerland 3,776,704 12/1973 Benjamin 75/.5 BC

3,814,635 6 1974 C '1. 148 11. [73] Assignee: The International Nickel Company, omen? at A l 5 R Inc., New York, NY, Primary E.\'aminer--W. Stallard Flledi P 11, 1973 Attorney, Agent, or FirmRaymond J. Kenny; Ewan 21 Appl. No.5 396,204 MacQueen 52 U.S. c1 148/11.5 F ABSTRACT [51] Int. C1. B22F l/00; B22F 3/14 S l pecla post extruslon workmg of mechanically a1- [58] Field of Search 148/11.5 F, 75/.5 BC loyed superanoys dispersiomstrengthened with an oxide of a lanthanide series metal results in improved [56] References and stress-rupture properties.

UNITED STATES PATENTS 3,346,427 10/1967 Baldwin et a1 148/1 1.5 F 9 Clam, D'awmgs POST WORKING F MECHANIALLY ALLOYED PRODUCTS The present invention is addressed to mechanically alloyed dispersion-strengthened materials, particularly nickel-base superalloys containing a lanthanide metal oxide dispersoid.

Mechanical alloying, described in US. Pat. Nos. 3,591,362 and 3,723,092 and incorporated herein by reference, involves, as is known, the dry and intensive milling of powders in high energy machines and under special conditions during which constituent powders are repeatedly fragmented and cold bonded by the continuous impacting action of attriting elements. This processing is continued for a period such that composite product powder particles of saturation, or at least substantial saturation, hardness are formed, the composition of which correspond to the percentages of the respective components in the original charge. By reason of this, the constituent powders become most intimately interdispersed at close interparticle spacings, the composite particles being exceptionally dense and homogeneous, and characterized by cohesive internal structures. A further attribute of this development is that it permits of precipitation hardening, dispersion strengthening and matrix stiffening to be brought together in one alloy, particularly the nickel and nickelchromium superalloys.

By far and large, practically all thermomechanical processing of mechanically alloyed superalloy composite particles has been accomplished by virtue of extrusion, with improved extrusion parameters having been recently developed as set forth in copending US. Pat. application 131,761. As extrusion has dominated the thermomechanical processing scene, so yttria and thoria have received virtually exclusive attention as the dispersoids. However, since cost is always an important factor, other oxide dispersoids have been investigated and this has brought forth an unexpected problem.

When thoria or yttria are used as the dispersoid, a highly satisfactory level of stress-rupture properties can be consistently achieved. However, with lathanide series metal oxides such as lanthana, ceria, didymia and the like, stress-rupture properties are often quite inferior. The complete theoretical mechanism which might explain this anomaly is not yet at hand, but an excess of fine grains is usually found subsequent to the conventional germinative grain growth heat treatment and this is considered responsible for the less attractive properties. In any case, it has been found that if mechanically alloyed superalloys dispersion hardened by one or more lanthanide metal oxides are hot worked as herein described subsequent to extrusion but prior to heat treatment, a high level of stress-rupture characteristics can nonetheless be obtained.

Generally speaking and in accordance herewith, the overall stress-rupture properties at elevated tempera tures of mechanically alloyed superalloys, notably the nickel and/or cobalt-base compositions, dispersionstrengthened by an oxide of a lanthanide series metal are markedly enhanced by extruding a compact of the composite alloy particles and thereafter hot working (as by forging or hot rolling) the extruded product under correlated conditions of temperature and reduction such that upon germinative grain growth heat treatment a product is produced having a coarse, elongated grain structure, there being few, if any, fine grains.

In terms of the mechanical alloying process itself, the initial powder charge should be carried out to the point of at least substantial saturation hardness, i.e., the level at which there is about at least a 50% difference between the base hardness of the alloy in the unworked condition and its saturated hardness in substantially the fully coldworked condition, this to provide mechanically alloyed powders of substantially homogeneous microstructure, such that upon examination of the structure of the powder at a magnification of, say, 250 diameters there is virtually no evidence of the starting material, the initial powder ingredients having been intimately united and interdispersed.

In the subsequent operations of extrusion (hot consolidation) of the composite powder and postconsolidation hot working, it is important that the working temperatures and reduction ratios be correlated to provide sufficiently worked consolidated bodies that can subsequently be heat treated to produce the desired coarse elongated grains. Underworked consolidated products generally result in small equiaxed grains when they are given the grain coarsening heat treatment while overworked consolidated products generally result in coarse equiaxed grains and/or cracking of the consolidated product during working. Working consolidated products at too low a temperature should be avoided to minimize the possibility of cracking during the working operation. It is accordingly important that the conditions of temperatures and reduction set forth herein be met.

Extrusion of the composite powder should be conducted at a temperature higher than about 1400F., so to achieve substantially 100% density in the consolidated product. The composite powder is preferably consolidated by hot extruding at a temperature of about 1600F. to 2100F. at an extrusion ratio of about 4:1 to 50:1.

Post extrusion hot working can be carried out as by hot forging or hot rolling, it being generally preferred that the amount of hot working be greater for alloys containing lower amounts of dispersoid material and less for higher dispersoid contents. For example, a reduction of about 20 to about 80% at about 1600F. can be used where the dispersoid content of the consolidated product is about 1 or l /z% or less, by volume, while about 10 to about 40% reduction at about 2000F. can be used where the dispersoid content is about 3% or more, with a reduction of about 20 to at 1800F. being advantageous with dispersoid contents of about 1.5 to about 3%.

Post extrusion hot working or hot rolling should preferably be conducted over the temperature and reduction ranges shown in Table I below, where the consolidated products contain about 0.5 to about 5%, by volume, lanthanide metal oxide dispersoid material having an average particle size of about 50 Angstroms to about 600 Angstroms.

(1900 to 2100) (20 to 60) TABLE I-Continued WORKING CONDITION Working Working Temp. Working Reduct. Dispersoid Operation (F.) approx. (approx.)

hot roll 1700 to 2100 I to 80 (I800 to 2050)* (20 to 60)* R.E.O.(b) hot forge I600 to 2000 10 to 60 (I750 to I900)* (15 to 45)* hot roll I700 to 2000 20 to 60 (I750 to 2000)* (25 to 45)* CeO hot forge 1700 to 2000 10 to 60 (I700 to I850) (I5 to 40)* Preferred (a)NominaI comp: 40-45% Ianthana, 32-37% neodymia, 8-I2% prueseodymia, balance oxides of other lanthanide metals.

(b)Nominal comp.: 24% lanthana, 48% ceria, 5% praeseodymia, 17% neodymia and alance essentially oxides of other lanthanide series metal.

Where stress-rupture properties at intermediate temperatures, e.g., 1400F., are important, the extruded products should be hot worked according to Table II.

TABLE II WORKING CONDITION Preferred The hot worked consolidated products described above are thereafter heated to attain coarse elongated grained products. A suitable temperature range is from about 2200F. or higher, up to the incipient melting point of the alloy for periods of about it to 4 hours. The coarsened grains thus produced generally will have average dimensions of about 500 to 5000 microns in length and about 50 to 1000 microns in width, and are elongated in the direction or directions of working. It is important that the hot working operation always precede the grain coarsening heat treatment and it is desirable that the exposure of the consolidated product to elevated temperatures, e.g., 2150F. or higher, prior to hot working be minimal and preferably be avoided, to avoid imparing the producibility of coarse, elongated grains by the grain-coarsening heat treatment subsequent to hot working.

EXAMPLE I An 8.5 kg powder charge containing 6.42 kg of nickel having an average particle size of 5 pm, 1.7 kg of Cr having an average size of 50 pm, 1.3 kg of a Ni- 8.5% Al-17% Ti master alloy with an average size of 50 pm, 0.02 kg ofa Ni-29% Zr (master alloy) and .003 kg of a Ni-18% boron master alloy and 0.153 kg of Ianthana having an average particle size of about 400 angstroms, prepared by calcining lanthanum oxalate at a temperature of 1300F., was mechanically alloyed in a IO-gallon capacity attritor for a period of 17 hours at an impeller speed of 182 rpm, the attritor being provided with 390 pounds of inch nickel pellets, which served as the attrition medium. Upon completion of the mechanical alloying, the minus 45 mesh fraction of the mechanically alloyed powder was packed in mild steel cans of 3 /2 inch diameter and the cans were sealed and extruded at 1900F. at ram speed of 0.5 linear feet per second to rectangular bars /8 by "/8 inches in crosssectional dimension, the extrusion reduction ratio being 16:1.

The consolidated alloy contained by weight, 20% chromium, 1.2% aluminum, 2.4% titanium, 0.07% zirconium, 0.007% boron, 2% volume lanthana having an average particle size of about 400 Angstroms, the balance being essentially nickel. A portion of the asextruded bar was heated at 2400F. for 2 hours without any prior hot working, and the product exhibited fine grains. Upon aging and the testing at 1900F., it was found that the stress-rupture life was virtually nil at 16,000 psi stress.

Pieces of the extruded bar were worked either by forging or rolling, at various elevated temperatures and various reductions (Tables III and IV), the reduction being applied to the inch dimension except where stated otherwise. In the rolling procedure, the reduction per pass was about 15%.

The thus-hot worked pieces were given a grain coarsening heat treatment of 2400F. for 2 hours and then were aged by heating at 1975F. for 7 hours and at 1300F. for 16 hours. Specimens from the grain coarsened-and-aged pieces were tested for stress-rupture properties at 1900F. and 1400F., the results being set out in Tables III and IV.

TABLE III I900F. Stress Rupture Properties La O Dispersoid Working Working Life Working Operation Temperature Reduction Stress(psi) (hours) El.

RA F.

Forging 1900 36 I 7 ,000 309.4 0.8 0 1800 45 20,000 5I8.2 2.5 0 1800 45 16,000 67.I*

18,000 276.2 1.25 0 I800 36 17,000 8.7 1.2 3.5 I700 29.5 17,000 3l6.9** 1.2 1700 29.5 16,000 475.8

TABLE III Continued 1900F. Stress Rupture Properties La O Dispersoid Working Working Life Working Operation Temperature Reduction Stress(psi) (hours) El.

RA F. "/0

18,000 l91.9** 2.5 Rolling 1800 29.5 22,000 37.7 3.7 7.0 1800 29.5 20,000 266.1 5.0 7.0 1800 29.5 18,500 428.3 3.7 0 1700 50.5 17,000 132.9 1.2 0

Specimen unbroken stess raised "Specimen unbroken A test discontinued grip or furnace failure.

TABLE IV 1400F. Stress Rupture Properties (La O Dispersoid) Working Working Life Working Operation Temperature Reduction Stress(psi) (hours) El. RA

Forging 1900 36 40,000 52.1 3.0 16.9 1800 36 40,000 34.3 5.0 14.0 1800 36 35,000 717.0*

37,500 73.8 3.8 8.5 1800 42 40,000 12.5 8.7 25.7 1700 29.5 40,000 19.4 8.5 20.6 1700 29.5 35,000 425.9 2.5 7.7 1600 27.5 40,000 6.3 7.5 13.9 Rolling 1800 29.5 40,000 6.4 13.7 28.0 1700 50.5 40,000 15.4 5.0 7.8

Specimen unbroken stress raised.

From Table 111, it can be seen that forging the lanthana-containing extrusions in the temperature range EXAM II of 1600F. to I900F. with reductions of about 27.5 to 45% and the grain coarsening at 2400F. provides 100- hour stress-rupture lives at 1900F. at stresses considerably greater than 17,000 psi, and that forging at 1800F. to reductions of 40.5 to 45% and grain coarsening provides 100-hour stress-rupture lives at stresses significantly higher than 20,000 psi at 1900F. These data compare well with the results obtained with respect to the as-extruded bar. Rolling the lanthanacontaining alloy at 1700F. to 1800F. to reduce it by about 29.5 to about 50.5% and then grain coarsening at 2400F. also provided 100 hour stress-rupture lives at 1900F. at stresses higher than 17,000 psi as seen from Table III. Rolling the lanthana-containing consolidated product at a temperature on the order of about 1800F. to achieve reductions on the order of 29.5% provided very good 1900F. stress-rupture properties at a stress of 20,000 psi and even 22,000 psi, so that rolling under such conditions and subsequent grain coarsening can provide, in such consolidated products, a IOO-hour life at 1900F. at an applied stress of about 21,000 psi. The 1400F. stress-rupture properties (Table IV) were generally good.

Metallographic examination of grain-coarsened pieces after the 2400F. grain coarsening treatment, revealed grains having average dimensions of about 1000 microns in length and about 80 microns in width. The grain structure was substantially uniform and no finegrained areas were evident.

An alloy similar in composition to that in Example I but having 2%% of a dispersoid mixture (herein refractory oxide mixture) comprising, by weight, 25% lanthana, 48% ceria, 17% neodymia, 5% praeseodymia and the balance essentially oxides of other lanthanide series metals (average particle size of about 350 Angstroms), was mechanically alloyed in the manner given in Example I, except the processing time was 20 hours. The minus 45 mesh fraction was sealed in mild steel cans and extruded at 1900F. at a reduction ratio of 16:1 to provide bar extrusions having a rectangular cross section of X 15/ 16-inch dimensions.

One piece of the extruded bar was annealed at 2400F. for 2 hours without prior hot working but no grain coarsening took place, this piece exhibiting a zero stress-rupture life at 1900F. and a stress of 16,000 psi. Other pieces were forged unidirectionally over the ranges of temperatures and reductions shown in Table V and then annealed at 2400F. for 2 hours to achieve grain coarsening, after which the grain-coarsened pieces were aged by heating at 1975F. for 7 hours and then at 1300F. for 16 hours. The thus-produced pieces were then tested for 1400F. stress rupture properties, results being shown in Table V. Specimens that were also tested at 1900F. at stresses of 16,000 and 18,000 psi exhibited lives of 703.8 and 130.9 hours, respectively, indicating the desirable elevated temperature properties obtainable with the present invention.

TABLE V 1400F. Stress Rupture Properties R.E.O. Dispersoid Working Working Life Working Operation Temperature Reduyction Stress(psi) (hours) El RA Forging 2000 39 40,000 135.6 2.5 7.0 1900 29.5 40,000 127.8 2.5 8.8 1900 29.5 45,000 41.8 3.7 8.7 1800 37.5 40,000 51.5 2.5 0.8 1800 37.5 45,000 28.7 1.25 O 1800 32.5 40,000 47.1 1.2 1800 22 40,000 263.9 6.2 10.0

Rolling 1800 29.5 40,000 84.6 1.2 10.0

EXAMPLE III A mechanically alloyed powder having a nominal composition similar to that in Example I except that the tions shown in Table VI and then grain coarsened by heating at 2400F. for 2 hours and stress-rupture tested at 1400F. From the stress-rupture test results given in Table VI, it can be seen that satisfactory intermediate dispersoid comprised about 2 /2 inch volume didymia temperature range properties were obtained.

TABLE VI 1400F. Stress Rupture Properties (Di o Dispersoid) Working Working Life Working Operation Temperature Reduction Stress(psi) (hours) E1. RA

Forging 2000 46.5 40,000 420.5 5.0 12.5 1900 46 40,000 117.6 2.5 7.0 1900 46 45,000 52.0 3.8 5.8 1800 34.5 40,000 274.8 2.5 7.8 1800 34.5 45,000 52.7 2.5 5.8 1800 29.5 40,000 253.5 5.0 12.7 1700 33 40,000 98.3 1.2 1.5 1700 33 40,000 24.6 1.25 O 1700 33 45,000 33.3 0.8 1.4 Rolling 1800 29.5 40,000 132.9 8.7 18.0 1800 29.5 45,000 40.9 6.2 4.0 1700 51 40,000 4.3 1.2

(153 grams, avg. particle size of 350 Angstroms) was EXAMPLE IV produced in the manner described in Example 1, except the mechanical alloying time was 20 hours.'The minus 45 mesh fraction of the powder was extruded at 1900F. with a 16:1 reduction ratio to produce by 15/16 inch rectangular cross-section bar. A piece of this bar was annealed in the as-extruded condition at 2400F. for 2 hours in an attempt to produce coarse elongated grains. Again, as excess of fine grains was found.

Other pieces of the bar were forged unidirectionally at, respectively, 1900F. and 2000F. to provide respective working reductions of about 46%. The thusworked pieces were then heated at 2400F. for 2 hours, which resulted in coarse elongated grains having average dimensions of about 100 microns wide and about 600 microns long, after which they were tested for stress-rupture properties at 1900F. The pieces worked at 2000F. were tested at stresses of 16,000 and 18,000 psi and had lives of 326.4 and 35.3 hours, respectively, while those worked at 1900F. were tested at stresses of 15,000 and 16,000 psi and had lives of 233.0 and 24.1 hours, respectively.

Pieces of other extrusions having the same composition and produced in the same manner as the extruded bar just described were forged over the temperature range of 1700F. to 2000F. to provide reductions over the range of about 29.5 to 46.5% as indicated in Table VI, after which they were graincoarsened by heating at 2400F. for 2 hours and then stress-rupture tested at 1400F. Other such pieces were rolled under the condi- TABLE VII 1900F. Stress Rupture Properties (CeO Dis ersoid) Forging Forging Temperature Reduction Stress Life (F.) (psi) (hours) E1. RA

Alloys that can be processed in accordance with the instant invention include those containing up to about 65% chromium, up to about 8% aluminum, up to about 8% titanium, up to about 40% molybdenum, up to 40% tungsten, up to about 20% columbium, up to about 40% tantalum, up to about 5% vanadium, up to about 15% manganese, up to about 0.5% magnesium, up to about 2% carbon, up to about 3% silicon, up to about 1% boron, up to 2%.zirconium, up to about 6% hafnium, up to about 40% iron, up to about 10% or more by volume of a dispersoid material comprising an oxide of lanthanide series metal, and the balance essentially nickel and/or cobalt.

It is generally preferred that the mechanically alloyed powder charge contain, by weight, about 5 to 35% chromium, at least one metal from the group of aluminum and titanium in a total amount of at least about 0.5 and up to about 13%, e.g., 0.5 to 6.5% of either or both aluminium and titanium, up to about 15% molybdenum up to about tungsten, up to about 10% columbium, up to about 10% tantalum, up to about 3% vanadium, up to about 2% maganese, up to about 2% silicon, up to about 0.75% carbon, up to about 0.1% boron, up to 1% zirconium, up to about 0.2% magnesium, up to about 35% iron and about 1 to 3%, e.g., 1.75% to about 2.5%, by volume, of dispersoid material comprising an oxide of lanthanide series metal. It is preferred that the dispersoid particles have an average particle diameter of about 20 to 2000 Angstroms, more preferably, about 50 to about 1000 Angstroms.

Although the invention has been described in connection with preferred embodiments, modifications may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such are considered within the purview and scope of the invention and appended claims.

I claim:

1. A process for achieving enhanced stress-rupture characteristics at elevated temperatures in respect of a mechanically alloyed superalloy composition containing as a dispersoid an oxide of a lanthanide series metal, whereby the alloy is capable of developing a desired structure having coarse elongated grains upon germinative grain growth treatment, which comprises hot consolidating a charge of such mechanically alloyed composite superalloy powder particles and thereafter hot working the resulting hot consolidated product, the temperature of hot working and amounts of reduction being correlated such that (a) the formation of small equiaxed grains upon grain coarsening heat treatment is minimized, and (b) the formation of coarse equiaxed grains and/or cracking of the consolidated product during the hot working operation is minimized, whereby coarse elongated grains result upon subsequent heating of the shape at germinative grain growth temperature.

2. A process in accordance with claim 1 in which the lanthanide metal series oxide dipsersoid is of the group lanthana, didymia, rare earth oxide and ceria, the lanthana, didymia, rare earth oxides being respectively either hot forged or hot rolled within the combination of hot working temperature range and hot working reduction range given below.

-Continued Working Working Temp. Working Reduct.

Dispersoid Operation (F.) approx. (approx.)

R.E.O.(b) hot forge 1600 to 2000 10 to 60 1750 to 1900 15 to 45 hot roll 1700 to 2000 20 to 60 (1750 to 2000) (25 to 45) CeO hot forge 1700 to 2000 10 to 60 (1700 to 1850) (15 to 40) 3. A process in accordance with claim 2 in which the hot forging or hot rolling operation is conducted in accordance with the following:

4. A process in accordance with claim 2 in which the dispersoid material is present in an amount of up to about 10% by volume.

5. A process in accordance with claim 2 in which the dipsersoid material is present in an amount of about 1 to 3% by volume.

6. A process in accordance with claim 1 in which the dispersion-strengthened mechanically alloyed superalloy is of a composition containing up to 65% chromium, up to about 8% aluminum, up to about 8% titanium, up to about 40% molybdenum, up to 40% tungsten, up to about 20% columbium, up to about 40% tantalum, up to about 5% vanadium, up to about 15% manganese, up to about 0.5% magnesium, up to about 2% carbon, up to about 3% silicon, up to about 1% boron, up to 2% zirconium, up to about 6% hafnium, up to about 40% iron, up to about 10% or more by volume of a dispersoid material comprising an oxide of lanthanide series metal, and the balance essentially nickel and/or cobalt.

7. A process in accordance with claim 1 in which the dispersion-strengthened mechanically alloyed superalloy is of a composition containing about 5% to about 35% chromium, about 0.5% to about 13% of metal from the group of aluminum and titanium, up to about 15% molybdenum, up to about 20% tungsten, up to about 10% columbium, up to about 10% tantalum, up to about 3% vanadium, up to about 2% manganese, up to about 2% silicon, up to about 0.75% carbon, up to about 0.1% boron, up to 1% Zirconium, up to about 0.2% magnesium, up to about 35% iron, and about 1 to 3% by volume of dispersoid material.

8. A process in accordance with claim 2 in which the hot worked product is heated at a temperature of from about 2200F. to below the incipient melting point of the alloy, whereby a microstructure is obtained having coarse elongated grains and few, if any, fine grains.

9. A process in accordance with claim 2 in which the dispersoid is of an average particle size of about to about 600 Angstroms. 

1. A PROCESS FOR ACHIVING ENHANCED STRESS-RUPTURE CHARACTERISTICS AT ELEVATED TEMPERATURES IN RESPECT OF A MECHANICALLY ALLOYED SUPERALLOY COMPOSITION CONTAINING AS A DISPERSOID AN OXIDE OF A LANTHANIDE SERIES METAL, WHEREBY THE ALLOY IS CAPABLE OF DEVELOPING A DESIRED STRUCTURE HAVING COARSE ELONGATED GRAINS UPON GERMINATIVE GRAIN GROWTH TREATMENT, WHICH COMPRISES HOT CONSOLIDATING A CHARGE OF SUCH MECHANICALLY ALLOYED COMPOSITE SUPPERALLOY POWDER PARTICLES AND THEREAFTER HOT WORKING THE RESULTING HOT CONSOLIDATED PRODUCT, THE TEMPERATURE OF HOT WORKING AND AMOUNTS OF REDUCTION BEING CORRELATED SUCH THAT (A) THE FORMATION OF SMALL EQUIAXED GRAINS UPON GRAIN COARSING HEAT TREATMENT IS MINIMIZED, AND (B) THE FORMATION OF COARSE EQUIAXED GRAINS AND/OR CRACKING OF THE CONSOLIDATED PRODUCT DURING THE HOT WORKING OPERATION IS MINIMIZED, WHEREBY COARSE ELONGATED GRAINS RESLT UPON SUBSEQUENT HEATING OF THE SHAPE AT GERMINATIVEGRAIN GROWTH TEMPERATURE.
 2. A process in accordance with claim 1 in which the lanthanide metal series oxide dipsersoid is of the group lanthana, didymia, rare earth oxide and ceria, the lanthana, didymia, rare earth oxides being respectively either hot forged or hot rolled within the combination of hot working temperature range and hot working reduction range given below.
 3. A process in accordance with claim 2 in which the hot forging or hot rolling operation is conducted in accordance with the following:
 4. A process in accordance with claim 2 in which the dispersoid material is present in an amount of up to about 10% by volume.
 5. A process in accordance with claim 2 in which the dipsersoid material is present in an amount of about 1 to 3% by volume.
 6. A process in accordance with claim 1 in which the dispersion-strengthened mechanically alloyed superalloy is of a composition containing up to 65% chromium, up to about 8% aluminum, up to about 8% titanium, up to about 40% molybdenum, up to 40% tungsten, up to about 20% columbium, up to about 40% tantalum, up to about 5% vanadium, up to about 15% manganese, up to about 0.5% magnesium, up to about 2% carbon, up to about 3% silicon, up to about 1% boron, up to 2% zirconium, up to about 6% hafnium, up to about 40% iron, up to about 10% or more by volume of a dispersoid material comprising an oxide of lanthanide series metal, and the balance essentially nickel and/or cobalt.
 7. A process in accordance with claim 1 in which the dispersion-strengthened mechanically alloyed superalloy is of a composition containing about 5% to about 35% chromium, about 0.5% to about 13% of metal from the group of aluminum and titanium, up to about 15% molybdenum, up to about 20% tungsten, up to about 10% columbium, up to about 10% tantalum, up to about 3% vanadium, up to about 2% manganese, up to about 2% silicon, up to about 0.75% carbon, up to about 0.1% boron, up to 1% zirconium, up to about 0.2% magnesium, up to about 35% iron, and about 1 to 3% by volume of dispersoid material.
 8. A process in accordance with claim 2 in which the hot worked product is heated at a temperature of from about 2200*F. to below the incipient melting point of the alloy, whereby a microstructure is obtained having coarse elongated grains and few, if any, fine grains.
 9. A process in accordance with claim 2 in which the dispersoid is of an average particle size of about 150 to about 600 Angstroms. 